When printing sheets between a rotatable print cylinder and a rotatable impression roll, the print cylinder is usually inked from an ink roll, often an anilox roll, having a film of ink thereon. In some printing machines or sections, the ink roll is inked by a wipe roll inking system. Whereas in other printing apparatus this is done by a doctor blade head having one or more doctor blades.
The two inking systems, i.e. wipe roll and doctor blade, have different inking characteristics. In the wipe roll system an ink fountain is usually formed in the upper nip trough between the wipe roll and the ink roll. Whereas in the doctor blade system, the fountain is often formed between two doctor blades in engagement with the ink or anilox roll.
The wipe roll inking system is good with thinner inks, poorer with thicker inks, but good for transferring large quantities of ink for broad printing coverage.
The doctor blade inking system is good with thicker inks, and good for fine-screen printing using a fine-screen engraved anilox roll. Also, the doctor blade system is better suited than the wipe roll system for use when it is desired to operate the ink roll at higher revolutions per minute.
If a printing machine capable of employing either inking system is required, then it has been necessary to include at least two printing sections, one having a wipe roll inking system and the other having a completely separate doctor blade inking system.